Battery housing for a drive battery

ABSTRACT

A battery housing for a drive battery, comprising at least one housing shell, wherein the housing shell is formed at least partially or fully from a thermoplastic, wherein the housing shell has a receiving region for insertion of a drive battery, wherein the housing shell has a wall, wherein the wall has a two-layer or multi-layer sandwich structure, wherein at least a first layer of the sandwich structure, at least in some sections, is distanced from a second layer of the sandwich structure such that a wall cavity is formed between the first layer and the second layer, and wherein the wall cavity is designed to store a cooling medium.

FIELD

The present invention relates to a battery housing for a drive battery.

BACKGROUND

Battery housings for drive batteries serve for reliably enclosing adrive battery, for example in a motor vehicle. In this case, the drivebattery should be accommodated in the battery housing so as to becrash-resistant and protected from fire for a specified minimum periodof time. In this manner, escape of chemicals which are environmentallyhazardous and harmful to health in the event of a crash or fire shouldbe avoided. Battery housings for drive batteries of motor vehiclestherefore have to pass standardized fire tests, such as are also knownfor example for fuel tanks of motor vehicles.

In order to comply both with the requirements in terms of crashresistance and the minimum requirements in terms of fire resistance,known battery housings for accommodating drive batteries are usuallymade from welded or pressed steel sheet or cast aluminum. In such case,it is a disadvantage that such housings made of metallic material arecomparatively heavy and therefore adversely affect the range ofelectrically powered vehicles.

SUMMARY

Given this background, the invention is based on the technical problemof devising a lightweight battery housing for a drive battery which inparticular is crash-resistant and is protected from fire for a specifiedminimum period of time.

A battery housing for a drive battery is specified, comprising at leastone housing shell, wherein the housing shell is formed at leastpartially or fully from a thermoplastic, wherein the housing shell has areceiving region for insertion of a drive battery, wherein the housingshell has a wall, wherein the wall has a two-layer or multi-layersandwich structure, wherein at least a first layer of the sandwichstructure, at least in some sections, is distanced from a second layerof the sandwich structure such that a wall cavity is formed between thefirst layer and the second layer, and wherein the wall cavity isdesigned to store and/or distribute a cooling medium.

The sandwich structure accordingly forms with the integrated wall cavityboth a structure for crash-resistant enclosing of a drive battery and avolume for storing and/or distributing cooling medium.

Due to the fact that in operation a cooling medium for cooling the drivebattery accommodated in the battery housing is stored within the wall,the fire resistance of the battery housing can be increased. Thus thecooling medium stored in the wall, in the event of a fire, also servesto cool the wall which is exposed to a fire.

The terms “drive battery” and “traction battery” are used synonymouslyin the present case. A drive battery or traction battery may further bereferred to as a high-performance storage battery, which is used in forexample in purely electrically powered vehicles or hybrid vehicles.

The cooling medium may be a refrigerant or a coolant. For example,according to one configuration of the battery housing a water/glycolmixture may be stored as coolant within the sandwich structure, i.e. inthe wall cavity of the sandwich structure. According to alternativeconfigurations, a refrigerant may be stored in the wall cavity. The wallof the housing shell is accordingly constructed in the manner of acavity profile.

According to a further configuration of the battery housing, provisionis made for a portion of the wall cavity to be an expansion volume forthe cooling medium. The cooling medium, which may be in particular acoolant or a refrigerant, may expand during cooling operation owing tothe introduction of heat from the drive battery, which is to be cooled,and/or changes at least partially by a phase change from the liquid intothe gaseous phase. The expansion volume provides the necessarycompensating volume for such operations.

Alternatively or additionally, provision may be made for an expansionvolume to be integrated in a cover which closes the housing shell, theexpansion volume of the cover being in a fluid connection with the wallcavity of the housing shell. In this case, a cavity integrated withinthe wall of the cover is in a fluid connection with the wall cavity ofthe housing shell, for example by way of a hose connection, pipeconnection, flanged connection or the like. Provision may be made forthe housing shell to be closable or closed with a conventional metalcover, which may for example be formed in part or fully of a steel oraluminum material.

In order to permit as compact a construction of a cooling means aspossible, a pump and/or a compressor for delivering the cooling mediummay be integrated, at least in some sections, in the sandwich structure.Accordingly, a cooling means for cooling a drive battery may beintegrated in part or fully in the battery housing.

For example, a pump and/or a compressor may, at least in some sections,be encompassed on two sides by the first layer of the sandwich structureand by the second layer of the sandwich structure. In particular, a pumpand/or a compressor may be fully encompassed by the first layer of thesandwich structure and the second layer of the sandwich structure. Inthis manner, the pump and/or the compressor are reliably protected fromenvironmental influences. It goes without saying that at least one powersupply line for supplying the pump and/or the compressor may beconducted through the wall.

The first layer and the second layer of the sandwich structure may,according to a further configuration of the battery housing, in somesections, be connected directly together. For example, the first and thesecond layer may, in some sections, be integrally bonded with eachother, in particular by welding and/or bonding. Thus substantiallylinear and/or substantially punctiform connections may be formed betweenthe first layer and the second layer in order to provide acrash-resistant, reinforced sandwich structure.

Alternatively or additionally, provision may be made for at least onereinforcing element or a plurality of reinforcing elements to extendbetween the first layer and the second layer, which elements aredesigned to stiffen the sandwich structure. Such a stiffening element isfor example a strut extending between the first and the second layer.The reinforcing element may have a circular, ovular or polygonal crosssection.

A reinforcing element may be connected by a first end to the first layerand be connected by a second end to the second layer. The reinforcingelement may in particular be welded to the first and the second layer.

Consequently, an arrangement of local connection points may be providedbetween the first layer and the second layer and/or reinforcing elementsin order to guarantee crash-resistant accommodation of a drive batteryor traction battery in the battery housing.

Provision may be made for at least one reinforcing element or aplurality of reinforcing elements to be of a multi-componentconfiguration, and to contain at least two materials. Thus thereinforcing elements or at least one reinforcing element may be formedat a first end from a first material which can be welded to a materialof the first layer, and at a second end distanced from the first end maybe formed from a second material which can be welded to the secondlayer. In particular, a respective reinforcing element may containmaterials which can be welded in each case in the same way to theassociated materials of the first layer and of the second layer in orderto achieve a reliable welded connection.

A central section formed between the ends of the reinforcing elementmay, compared with its end connection regions, be formed from a stifferor more flexible material in order to guarantee sufficient flexibilityand/or stiffness of the housing shell depending on the loadingcondition.

Alternatively or additionally, provision may be made for at least onereinforcing element or a plurality of reinforcing elements to have apredetermined breaking point. The predetermined breaking point allowsthe corresponding reinforcing element to fail or to absorb energy in theevent of an overload, so that damage to the drive battery which is to beenclosed from parts of the battery housing is avoided.

The battery housing may have cooling fins for dissipating heat to thesurroundings on the housing shell or a cover which closes the housingshell. With the aid of the cooling fins, a surface enlargement can bebrought about in known manner, so that a heat transfer from the coolingmedium towards the surroundings can take place.

If cooling fins for dissipating heat are formed for example on the wallof the housing shell and/or are formed on a cover which closes thehousing shell, a cooler may be integrated fully in the battery housing.

Alternatively or additionally, the wall cavity can be placed in a fluidconnection with an external cooler which is separate from the batteryhousing. To this end, two or more interfaces for coupling a cooler inletand a cooler outlet may be integrated in the wall of the housing shelland/or the cover in order to form a cooling circuit.

The housing shell can be produced inexpensively and efficiently by blowmolding. Blow molding permits a one-layer or multi-layer wallconstruction in a reliable manner, it being possible in addition forreinforcing elements to be applied during the blow molding process inthe shaping heat.

Alternatively, the housing shell may have been produced in part byinjection molding. Injection molding permits a multi-layer wallconstruction in an inexpensive manner.

The first layer of the sandwich structure may be of multi-layerconstruction. Thus the first layer of the wall structure may for itspart in turn consist of a plurality of layers of thermoplastic. Thisapplies equally for the second layer, which may likewise, taken byitself, in turn be of multi-layer construction. Thus a plurality ofmaterials can be combined in order to meet the requirements relating tostiffness, flexibility, pollutant emission and fire protection.

Provision may be made for at least one of the layers to have a barrierlayer which serves as a diffusion barrier for hydrocarbons. In suchcase, this may for example be a layer of EVOH (ethylene/vinyl alcoholcopolymer).

At least one of the layers may consist of polyamide (PA), polypropylene(PP), polyphthalamide (PPA), polyphenylene sulfide (PPS), polyketone(PK) or polyethylene (PE), or contain polyamide (PA), polypropylene(PP), polyphthalamide (PPA), polyphenylene sulfide (PPS), polyketone(PK) or polyethylene (PE).

At least one of the layers may consist of a fiber-reinforced plasticsmaterial or contain fiber-reinforced plastics material. Due to thefiber-reinforced plastics material, a lightweight and at the same timerigid sandwich material can be provided in a simple manner.

At least one of the layers may have been shaped by thermoforming. Thus,for example, one layer of the sandwich material or the entire sandwichmaterial can be brought per se into the intended form by heating andsubsequent shaping, in order to define a receiving region for insertionof the traction battery or drive battery.

At least one of the layers may contain an organo sheet or consist of anorgano sheet.

Alternatively or additionally, the housing shell may be clad with organosheet on an outer side distanced from the receiving region. Thus thefire resistance of the housing shell can be increased and in additionreinforcement of the housing shell obtained.

Provision may be made for at least one of the layers to contain anelectrically conductive material in order to comply with current EMCstandards, for example from the automobile sector.

Provision may be made for one or more retaining clamps or retainingtabs, which contain an organo sheet, to be provided for fastening thebattery housing to a vehicle body. The organo sheet may in this case becurved in the manner of a hook and have at least one through-hole inorder to permit the housing shell to be screwed to a vehicle body. Theretaining clamps or retaining tabs may be incorporated in the sandwichstructure in an integrally bonded manner, in particular by welding,encapsulation or bonding.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention will be described in greater detail with referenceto drawings which illustrate embodiments. These show, in each caseschematically:

FIG. 1 is a battery housing according to the invention for a drivebattery;

FIG. 2 is a first wall cross section of the housing shell of FIG. 1;

FIG. 2B is a second wall cross section of the housing shell of FIG. 1;

FIG. 3 is a layered construction of a first layer of the housing shellof FIG. 2B;

FIG. 4 is a further battery housing according to the invention with acooler;

FIG. 5 is a perspective view of and a cross section through a retainingclamp for a battery housing according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a battery housing 2 according to the invention for a drivebattery. The battery housing 2 has a housing shell 4 which can be closedwith a cover 7. An intermediate plate 9 in the present case is shown astransparent and is merely indicated in a position lifted off from thehousing shell 4, in order to ensure clarity of the drawing.

The housing shell 4 and the cover 7 in the present case are formedsubstantially fully of a thermoplastic. The housing shell 4 has areceiving region 6 for insertion of a drive battery. Above theintermediate plate 9, battery modules of the drive battery can likewisebe accommodated.

The housing shell 4 has a wall 8, the wall 8 having a multilayersandwich structure 10 (FIG. 2A; FIG. 2B). A first layer 12 of thesandwich structure 10, at least in some sections, is distanced from asecond layer 14 of the sandwich structure 10 such that a wall cavity 16is formed between the first layer 12 and the second layer 14. The wallcavity 16 is designed for storing a cooling medium.

FIGS. 2A and 2B show schematically the construction of the sandwichstructure 10. It goes without saying that the spaces 16 illustrated inFIG. 2B are in a fluid connection and as a whole form the wall cavity 16for storing cooling medium. One portion of the wall cavity 16 is anexpansion volume for the cooling medium.

In the regions 18, the first layer 12 and the second layer 14 arelocally welded together. The sandwich structure 10 has openings 20 andis penetrated by connecting elements 22.

Between the first layer 12 and the second layer 14, there are arrangedreinforcing elements 24 which are designed to stiffen the sandwichstructure 10.

Such a reinforcing element 24 is of a two-component construction andcontains at least two materials which are welded in the same way to thefirst layer 12 and the second layer 14. The reinforcing element 24 has apredetermined breaking point 26.

As shown in FIG. 3 as an example for the first layer 12 of FIG. 2B, eachof the layers 12, 14 may for its part in turn be of multi-layerconstruction in the manner of a sandwich structure. Thus the first layer12 in the present case has an outer layer in the form of an organo sheet28, which covers a plastics material 30 provided with conductive filler.The plastics material 30 provided with conductive filler may beconnected by means of a coupling agent layer 32 to a barrier layer 34which is connected by a further coupling agent layer 36 to a furtherplastics-material layer 38.

FIG. 4 shows a further liquid container 40 according to the inventionwhich has a pump 44 embedded in a sandwich structure 42. By way of thepump 44, a wall cavity 46 of the container 40 is in a fluid connectionwith a cooler 48, so that a cooling medium stored in the wall cavity 46can be circulated via the cooler. The battery housing 40 has a receivingregion 50 which is designed for receiving a drive battery or tractionbattery. On the container 40 there are provided cooling fins 51 fordissipating heat to the surroundings.

FIG. 5 shows a retaining clamp 52 which has an organo sheet 54encapsulated with plastics material 56, in order to screw a batteryhousing 2 or 40 to a vehicle body. To this end, the retaining clamp 52may be penetrated by a sleeve 58. The plastics material 56 may forexample be polypropylene or polyamide. The holding element 54 may beable to be welded to the battery housing 2 or 40 and thus be connectedto a sandwich structure 10 or 42 in an integrally bonded manner.

REFERENCE NUMERALS

-   2 battery housing-   4 housing shell-   6 receiving region-   7 cover-   8 wall-   9 intermediate plate-   10 sandwich structure-   12 first layer of the sandwich structure 10-   14 second layer of the sandwich structure 10-   16 wall cavity-   18 regions-   20 openings-   22 connecting element-   24 reinforcing element-   26 predetermined breaking point-   28 organo sheet-   30 plastics material-   32 coupling agent layer-   34 barrier layer-   36 coupling agent layer-   38 plastics-material layer-   40 liquid container-   42 sandwich structure-   44 pump-   46 wall cavity-   48 cooler-   50 receiving region-   51 cooling fins-   52 retaining clamp-   54 organo sheet-   56 plastics material-   58 sleeve

What is claimed is: 1-10. (canceled)
 11. A battery housing for a drivebattery, comprising at least one housing shell, wherein: the housingshell is formed at least partially or fully from a thermoplastic; thehousing shell has a receiving region for insertion of a drive battery;the housing shell has a wall; the wall has a two-layer or multilayersandwich structure; at least a first layer of the sandwich structure, atleast in some sections, is distanced from a second layer of the sandwichstructure such that a wall cavity is formed between the first layer andthe second layer; and the wall cavity is designed to store and/ordistribute a cooling medium.
 12. The battery housing according to claim11, wherein: a portion of the wall cavity is an expansion volume for thecooling medium; and/or an expansion volume is integrated in a coverwhich closes the housing shell, the expansion volume of the cover beingin a fluid connection with the wall cavity of the housing shell.
 13. Thebattery housing according to claim 11, wherein a pump and/or acompressor are integrated, at least in some sections, in the sandwichstructure.
 14. The battery housing according to claim 11, wherein thefirst layer and the second layer, in some sections, are connecteddirectly together.
 15. The battery housing according to claim 11,wherein at least one reinforcing element or a plurality of reinforcingelements extend(s) between the first and second layer, which elementsare designed to stiffen the sandwich structure.
 16. The battery housingaccording to claim 15, wherein: at least one reinforcing element or aplurality of reinforcing elements are of multicomponent configuration,and contain at least two materials; and/or in that at least onereinforcing element or a plurality of reinforcing elements has/have apredetermined breaking point.
 17. The battery housing according to claim11, wherein: cooling fins for dissipating heat to the surroundings areprovided; and/or the wall cavity can be placed in a fluid connectionwith an external cooler by way of at least one connector.
 18. Thebattery housing according to claim 11, wherein: the housing shell hasbeen produced by blow molding; or the housing shell has been produced atleast partially by injection molding.
 19. The battery housing accordingto claim 11, wherein: the first layer is a multilayer one; and/or thesecond layer is a multilayer one; and/or at least one of the layers hasa barrier layer which serves as a diffusion barrier for hydrocarbons;and/or at least one of the layers contains polyamide, polypropylene,polyphthalamide, polyphenylene sulfide, polyketone or polyethylene, orconsists of polyamide, polypropylene, polyphthalamide, polyphenylenesulfide, polyketone or polyethylene; and/or at least one of the layersis fiber-reinforced; and/or at least one of the layers has been shapedby thermoforming.
 20. The battery housing according to claim 11,wherein: at least one of the layers contains an organo sheet; and/or thehousing shell is clad with organo sheet on an outer side distanced fromthe receiving region; and/or at least one of the layers contains anelectrically conductive material; and/or one or more retaining clamps orretaining tabs, which contain an organo sheet, are provided forfastening to a vehicle body.